I am trying to figure out something for my father in law. This persistent popup keeps interrupting anything anyone is doing on his desktop by requesting he put in his password. I told him not to. It seems odd that Google would be so intrusive and I also can't highlight or click any of the area the arrow points to, also odd. It seems like it may be a phishing for password thing but I might be wrong. I'm using Teamviewer right now and I can't see the end of the http so that also seems strange. Any help would be greatly appreciated ! thanks in advance, Claire
Based on what you provided we can see that the Thunderbird icon is active.
If it was configured to synchronise with Gmail account, and the authorisation was never performed or revoked, the connection is refused by Gmail service and Thunderbird requests an OAuth authorisation.
If the above is true, there's no indication this authorisation request is illegitimate.
If Thunderbird is running constantly or checking the emails periodically, the message may appear on each connection attempt.
Because the authorisation is performed within an embedded browser session within Thunderbird, it doesn't behave like a regular browser, where you can check the certificate by clicking on the padlock icon.